During the next year we will initiate experiments using the new antibodies which we have prepared to attempt to determine the direction of growth (the addition of subunits to tail tubes to determine whether a built-in polarity exists). We also plan to prepare large quantities of tail tubes for x-ray diffraction. The idea is that we may be able to compare the tail tube-baseplates, which appear to be filled with something, with artificially emptied tubes which we know to be hollow. These will be compared by examining oriented gels of pellets of purified tail tubes by low angle x-ray diffraction in our laboratory. These experiments will be repeated using bacteriophage SPO1 to confirm the results obtained with bacteriophage T4. We intend to continue our efforts begun during the first year on the identification of T4 gene products by surface labeling with chloroglycoluril. This will also be extended to bacteriophage SPO1. The remarkably high specific activities will permit us to proceed rapidly with some of our in vitro assembly characterizations as well, and will facilitate our search for such things as a length determining molecule inside the tail tube.